Broken country flags emoji rendering in KDE

With the new emoji segmenter support in Qt 6.9, there is now broken rendering of country flag emojis in KDE. 

This is reproducible with Plasma systemsettings, when you go to Keyboard → Add Layout, the dialog that appears look like:

While before or with QT_DISABLE_EMOJI_SEGMENTER=1 it looks like:

The keyboard KCM is using https://invent.kde.org/frameworks/kguiaddons/-/blob/master/src/util/kcountryflagemojiiconengine.cpp